10 GHz Surface Acoustic Wave Filters with Narrow-Gap Interdigital Transducer Structure

Controllable well-insulated gaps between electrodes can be obtained by anodic oxidation of the edges of the regions of an Al film covered by photo resist. This technique is used to fabricate surface acoustic wave narrow gap interdigital transducers (NG-IDTs) and narrow gap floating electrode type unidirectional transducers (NG-FEUDTs). Experimental results indicate that the SAW NG-IDTs and NG-FEUDTs operate in the 10GHz range and have an electrode width of less than 0.2 µm.